New Hampshire and Vicinity Continental Shelf: Sand and Gravel Resources
|Title||New Hampshire and Vicinity Continental Shelf: Sand and Gravel Resources|
|Authors||Ward, LG, McAvoy, ZS, Vallee-Anziani, M|
|Volume||BOEM/New Hampshire Cooperative Agreement (Contract M14ACOOO10) Technical Report|
|Number of Pages||97|
|Organization Name||Bureau of Ocean Energy Management (BOEM) Marine Minerals Branch|
|Keywords||continental shelf, Gravel, Maps, New Hampshire, Sand, Seismics|
Based on the synthesis of relatively recent high-resolution bathymetry, new surficial sediment and geoform maps, and an extensive data archives that includes over ~1280 km of seismic profiles, ~1200 grain size analyses, and 23 vibracores, the distribution of sand and fine gravel was evaluated for the New Hampshire and vicinity continental shelf. This work heavily utilized the results of previous research on sand and gravel resources on the New Hampshire shelf by Birch (1984) and others. Unfortunately, much of the archived data was collected before the Global Navigation Satellite System (GNSS) was used routinely for navigation on research vessels. Consequently, much of the critical data from the archives has large uncertainty associated with the positioning. Furthermore, the seismics are of variable quality. Nevertheless, the data archives coupled with the recent high-resolution bathymetry and surficial sediment mapping provides the bases to develop an initial or 1st order evaluation of the sand and gravel resources and identify areas where follow-up field campaigns are warranted.
To date, five potential sites where sand and fine gravel deposits may be located in quantities suitable for extraction for beach nourishment have been identified. This report focuses on four of these sites due to the availability of seismics and vibracores. The most promising sites are referred to in this study as the Northern Sand Body (NSB) and the Southern Sand Deposits (SSD). Estimates of the volume of sand and fine gravel potentially available in the NSB and the SSD are on the order of 17.3 million m3 and 16.4 million m3, respectively. However, these values represent the total volume in area defined by subbottom seismics and include very fine sand and mud. Therefore, the volume of material that may be available for beach nourishment is likely considerably less. Both of these areas, as well as other potential sites identified, need to have high-resolution seismic surveys and vibracoring to fully evaluate the potential of the New Hampshire and vicinity continental shelf sand and fine gravel resources.
The New Hampshire continental shelf has extensive marine modified glacial deposits and associated marine formed shoals. The marine formed features, as well as some of the offshore eroded drumlins, are hypothesized as possible targets for marine mineral resources and will be examined in greater detail in future studies. Some of these deposits may represent significant sand and gravel deposits on the New Hampshire and vicinity continental shelf that have potential for future use for beach nourishment and other efforts to build coastal resiliency.